Depression. In last 2 years. help me. ?

My mom is suffering from depression. Her symptoms are like. She wants to talk non-stop, mostly fighting and cursing people (mostly dad). She has lot of false assumptions. We try to make her understand that nothing is wrong around her and everything is on right path. But she refused to accept it and always think negative. Like if the milkman gets late to bring milk she calls dad, who is busy with clients in the office, and starts fighting with him. Dad gets on average 7 to 8 calls daily from her, where he has to face her Infront of clients. The thing is she never listens to what we say. She regularly talks about seeing known faces from r relatives on TV. like seeing her sister, me, dad's sister which is not true. But she regularly talks about seeing known faces on TV. She has been behaving like this for last 2 years. It's like she is not in control of her mind. My mom was not like this. She is very easy going woman and friendly in nature which has changed in last 2 years. Help me. ??